dirty chunks on bitmap not clearing (RAID1)

[aristizb@ualberta.ca]

Hello,

I have a RAID1 with 2 LVM disks and I am running into a strange  
situation where having the 2 disks connected to the array the bitmap  
never clears the dirty chunks.

I am assuming also that when a RAID1 is in write-through mode, the  
bitmap  indicates that all the data has made it to all the disks if  
there are no dirty chunks using mdadm --examine-bitmap.

The output of cat /proc/mdstat is:

md2060 : active raid1 dm-5[1] dm-6[0]
       2252736 blocks [2/2] [UU]
       bitmap: 1/275 pages [12KB], 4KB chunk, file: /tmp/md2060bm


The output of mdadm --examine-bitmap /tmp/md2060bm is:

Filename : md2060bm
            Magic : 6d746962
          Version : 4
             UUID : ad5fb74c:bb1c654a:087b2595:8a5d04a9
           Events : 12
   Events Cleared : 12
            State : OK
        Chunksize : 4 KB
           Daemon : 5s flush period
       Write Mode : Normal
        Sync Size : 2252736 (2.15 GiB 2.31 GB)
           Bitmap : 563184 bits (chunks), 3 dirty (0.0%)


Having the array under no IO, I waited 30 minutes but the dirty data  
never gets clear from the bitmap, so I presume  the disks are not in  
sync; but after I ran a block by block comparison of the two devices I  
found that they are equal.

The superblocks and the external bitmap tell me that all the events  
are cleared, so I am confused on why the bitmap never goes to 0 dirty  
chunks.

How can I tell if the disks are in sync?


Thank you in advance for any help.


-- 
Juan Aristizabal